This invention relates to agricultural balers for producing the so-called square or rectangular type of bale, as opposed to the cylindrical or round bale. More specifically, the invention relates to such balers which produce relatively large square bales and are constructed differently from the balers producing smaller square bales.
The principle difference between the small and large square balers is that in the former, the bale case in which a bale is actually formed has wads of crop material delivered to it from a feeder duct positioned to one side of the bale case, whereas in the latter, the feeder duct is located beneath the bale case, whereby the latter is bottom fed. Furthermore, the cross-sectional area of the bale case of the large baler is considerably greater than that for the small baler, whereby the wad of crop material periodically fed to the bale case is correspondingly larger. It is desirable to provide a relatively compact wad of crop material in the feeder duct in order to ensure a relatively constant density of the bale being formed but in the case of a large baler with the greater amount of crop material involved, this can give rise to plugging of the feeder duct when, for example, normally dry crop is damp when being baled, or naturally moist crop, such as silage, is being baled. Traditionally, silage has been stored in silos but this requires the use of a forage harvester in order to pick up crop material and chop it into small pieces. Normally a trailer moves alongside the forage harvester and into which crop material is blown by the machine. The trailer then transports the crop material from the field to the place of storage. If a tower silo is employed, then a blower is required to transfer the silage from the trailer to the tower. Farmers are looking increasingly to the use of a baler for operating on silage because the machine is normally available to him as it is required to bale other crops and the handling and storage of bales of crop material is that much more convenient. On the other hand if any specialised equipment is required in this respect, then again it is normally available to the farmer as he will be using it to handle bales of other crop material.
The use of a baler for baling silage means that there is an increased risk of the feeder duct to the bale case becoming plugged. The general problem of plugging has been addressed in the past and steps taken to reduce the likelihood thereof, such as by the use of expandable feeder ducts as disclosed in U.S. Pat. No. 2,552,888; British Patent No. 2,059,869 and Dutch Patent No. 7807102, for example. However, these measures cannot be guaranteed to prevent plugging of the bale case feeder duct and when plugging occurs, it is extremely difficult, and hence time consuming, to remove the plug of crop material. This is because ready access to the feeder duct cannot be gained (even if the pick-up device is removed) and even if it could, it is not an easy task manually to pull the plug of crop material from the feeder duct because the plug is very tightly wedged in the duct and the crop feeder mechanism present in the duct aggravates the problem. Indeed, the plug is so often tightly wedged that even the feeder mechanism operable to feed crop material into the feeder duct cannot be reversed in order to help remove the plug of crop material.